Torque Converter

[puller]

I have a question about locking the torque converter so you can keep the transmission running cooler and have less strain on the truck. I have a transmission gauge and sender that I got from Geno's garage, as well as a Derale transmission cooler with a fan. I still see higher temps that I feel comfortable with when pulling up a mountain ar when in stop and go traffic. So how do you insure that the torque converter is locked to keep the temps down?



Thanks,



Puller

 

[rscurtis]

Where are you measuring the temperature? If it is the output line to the cooler, the high temps. will do nothing but alarm you, they are normal in that part of the system. Measuring the temperature in the pan will tell you the temp. going into the transmission and torque converter. When the pan temperature reaches an unsafe level, then you know you are over working the system.



You don't measure the temperature of your house by the water leaving the boiler or the refrigerant leaving the evaporator, the same logic applies to a transmission.

 

[JJPage]

You can manually lock the TC by grounding the #7 pin on the gear selector sensor. The sensor is located on the drivers side of the transmission, has an electrical harness plugged into it. Unlatch and pull the plug, on the face of the plug the pins are identified by number. Splice into the #7 conductor and run the new conductor through a single pole switch to ground. You have to also place a 22ohm resistor in the circuit, it doesn't matter which side of the switch. This resistor keeps ecm/pcm(03/04) from throwing codes and putting your truck into limp mode.



Some folks have used a 10ohm resistor, it was too close to the lower spectrum of the scale and was throwing codes on my truck, so I went with the 22ohm resistor and it works great.



You can also do the same to #6 pin conductor, this will lock your trans in OD.



Jess

 

[cerberusiam]

The first question is what temps do you feel are too high?



When are they occuring?





Using TH will significantly enhance the lockup strategy if engaged. Are you using it when pulling hard?

 

[puller]

The temps that I am expercing are in the 220 to 250 range when pulling very steep mountains. or when you have tp stop midway on a hill and start off from a dead stop or when in stop and go traffic or when backing up. All of these situations create temps higher than I feel comfortable with. The sender is on the output line from the transmission just before the first factory cooler.



Now I really do not want to change wiring, is there a way you can force the locking of the torque converter by changing gears down to 2nd or 1st or by selecting out of the tow haul mode to something else?



Thanks,



Puller

 

[cerberusiam]

Seeing 220-230 in stop-n-go traffic, or pulling a steep grade or in reverse up a grade is going to be pretty normal. With the stock TC its even worse because it spins harder and longer in fluid coupling than a tighter TC, but even with a better TC I will see those temps in those conditions.



As long you keep it in the range you see and its not running that for hours on end its normal. Remember you are seeing the hottest fluid in the trans at that point, the heat exchnager will bring the temp down to coolant temp and the front cooler will take another 40-50 degrees off the temp so the actual fluid temp in the trans is more like 160-170 and thats almost the middle of the suggested range for AT+4.



What you are seeing is the exact reason to have the temp probe in the hot line to adjust driving style. What you can try on the slow grades and stop and go is manual shifting down to 2nd and see if that helps. The TC will lock in manual 2nd but its not as aggressive as th eother gears. It spends a lot of time in fluid coupling to accelerate and if you have give a lot of throttle it doesn't want to lock until late. Same with drive, the lockup strategy is just not that great under heavy loads. Reverse is always going to be hot, just limit the time and the temp is all you can really do.



If you are pulling osme steep grades where 2nd gear or drive is adequate a mystyery switch to manually lock the TC is a good addition. I use mine frequently in conditions like that to keep the temps and rpms down. In stop and go driving there is not much you can do unless you have long stretches where your under power. The switch will hold the TC locked and kill the engine with lots of loud nasty noises. :-laf You really have to be on it to use in that situation.



The switch is pretty easy to install and it will help a lot in certain situations but its not a silver bullet for every thing.

 

[puller]

Thanks that is the information that I was looking for, I feel more comfortable driving the truck and pulling the fifth wheel now.





Puller